KR20050085789A - Water-dispersing plastic bodies and method for the production thereof - Google Patents

Abstract

The invention relates to water-dispersing plastic bodies made of a plastic substrate, at least one water-dispersing, inorganic coating (a) and an adhesive promoting intermediate layer (b) which is arranged between the plastic substrate and the inorganic coating. The invention is characterised in that the intermediate layer comprises two polymers (A) and (B), whereby water on one layer of the polymer (A) forms an edge angle which is smaller than or equal to 73° at 20 °C and water on one layer of the polymer (B) forms an edge angle greater than or equal to 75° at 20 °C.

Description

Water dispersible plastic bodies and method for manufacturing thereof

The present invention relates to a water droplet suppressing plastic article comprising a plastic substrate, an inorganic film that inhibits water droplet formation and an adhesion promoting intermediate layer located between the plastic substrate and the inorganic film.

The water present on the surface of the plastic product which inhibits the formation of droplets is not coalesced and is present as independent droplets, but instead flows together upon contact with droplet diffusion to form a cohesive layer. As a result, the light reflection is improved on the surface moistened with moisture-in the case of transparent plastics-excellent in permeability, and less likely that the droplets fall off the bottom of the plastic product.

Numerous attempts have been made to produce antifouling coatings coated with hydrophilic polymers crosslinked on waterproof plastic surfaces.

According to German Patent Publication No. 21 61 645, this type of coating is a copolymer of alkyl esters, hydroxyalkyl esters and quaternary aminoalkyl esters of acrylic or methacrylic acid and methyl of methacrylamide as crosslinking agent. Prepared from all ethers. This coating initially swells by absorbing water, and as a result is gradually converted into a form that suppresses the formation of water droplets. However, such a swelling softens the coating and is susceptible to mechanical damage.

EP 0 149 182 also describes a product which inhibits the formation of water droplets. Such plastic products include inorganic coatings based on SiO ₂ .

However, the drawback of the plastic products described in EP 0 149 182 and which inhibits the formation of water droplets completely loses the properties of inhibiting water formation when such plastic products are thermoformed, resulting in the formation of The film on the product is cloudy and unattractive.

Thus, in view of the prior art discussed and presented herein, it is an object of the present invention to provide a water droplet inhibiting plastic product, which has no side effects on the suppressive properties of water droplet formation and can be thermoformed without any turbidity. will be.

Therefore, another object of the present invention is to provide a water droplet suppressing plastic article, in which the film which inhibits water droplet formation has a particularly high adhesion to the plastic substrate. This property should not be affected by moisture.

It is a further object of the present invention to provide a plastic product which is highly durable, in particular resistant to UV radiation and highly weatherable.

It is a further object of the present invention to provide a water droplet suppressing plastic product, which can be produced in a particularly simple manner. For example, the substrate that can be used to make the plastic product should be a substrate that can be obtained, in particular, by extrusion molding, injection molding or other casting process.

It is still another object of the present invention to provide a water droplet suppressing plastic article having excellent mechanical properties. This property is particularly important for increasing the impact resistance of plastic products.

In addition, plastic products should have particularly good optical properties.

Another object of the present invention is to provide a plastic particle whose size and shape can be easily adjusted according to the requirements.

The plastic product described in claim 1 achieves this object and, without special mention, achieves another object which leads to a clear or necessary conclusion about the situation discussed herein. A useful variant of the plastic article of the invention is protected by the subclaims of claim 1.

Claim 24 achieves a potential object with respect to the manufacturing process.

In water-inhibiting plastic products, which have no side effects on the inhibiting properties of water droplet formation and can be thermoformed without any turbidity, the water adhesion inhibiting intermediate layer (b) has two polymers (A) and a polymer (B). A water droplet suppressing inorganic coating (a) comprising water and forming a contact angle of 73 ° or less in the polymer (A) layer at 20 ° C., and water forming a contact angle of 75 ° or more in the polymer (B) layer at 20 ° C .; It can be obtained when located between plastic substrates.

In particular, the advantages achieved by the present invention are as follows:

The film which inhibits the formation of water droplets on the plastic product according to the invention has a particularly high adhesion to the plastic substrate, and this property is also unaffected even when exposed to moisture.

Plastic products of the present invention have high resistance to UV radiation.

Plastic products of the present invention can be manufactured at low cost.

Plastic products of the invention may be suitable for specific requirements. In particular, the size and shape of plastic products can vary widely without affecting moldability at all. In addition, the present invention also provides a plastic product having excellent optical properties.

The mechanical properties of the plastic product of the present invention are excellent.

The plastic article of the present invention can be obtained by coating a plastic substrate. Plastic substrates suitable for the purposes of the present invention are known per se. Such substrates are in particular polycarbonates, polystyrenes, polyesters such as glycol modified polyethylene terephthalate (PET), polybutylene terephthalate (PBT), cycloolefinic polymers (COCs) and / or poly (meth) acrylics Includes the rate. Preferably, they are polycarbonates, cycloolefinic polymers and poly (meth) acrylates, particularly preferably poly (meth) acrylates.

Polycarbonates are well known to those skilled in the art. Polycarbonates are regarded as polyesters consisting of external carbonic acid and aliphatic or aromatic dihydroxy compounds. This can be readily obtained by reacting diglycol or bisphenol with phosgene or carboxylic acid diester in a polycondensation or transesterification reaction.

Preferably, it is a polycarbonate derived from bisphenol. Especially among these, bisphenol is 2, 2-bis (4-hydroxyphenyl) propane (bisphenol A), 2, 2-bis (4-hydroxyphenyl) butane (bisphenol B), 1, 1-bis (4-hydroxy) Oxyphenyl) cyclohexane (bisphenol C), 2,2'-methylenediphenol (bisphenol F), 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane (tetrabromobisphenol A ) And 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane (tetramethyl-bisphenol A).

Such aromatic polycarbonates are generally prepared by interfacial polycondensation or transesterification reactions and described in Encycl. Polym. Sci. Engng. 11, 648-718.

In interfacial polycondensation, bisphenols in the form of an aqueous alkaline solution are emulsified in an inert organic solvent such as methylene chloride, chlorobenzene or tetrahydrofuran and react with phosgene in a reaction related step. Amines are used as catalysts and phase transfer catalysts are used in the case of sterically hindered bisphenols. The resulting polymer is dissolved in the organic solvent used.

The properties of the polymer can vary widely by selecting bisphenols. If different bisphenols are used together, the block polymer can also be prepared by multistage polycondensation.

Cycloolefinic polymers are polymers obtainable using cyclic olefins, in particular polycyclic olefins.

Cyclic olefins are, for example, monocyclic olefins such as cyclopentene, cyclopentadiene, cyclohexene, cyclopeptene, cyclooctene, and alkyl derivatives of monocyclic olefins having 1 to 3 carbon atoms, for example For example methyl, ethyl or propyl such as methylcyclohexene or dimethylcyclohexene, and acrylate and / or methacrylate derivatives of such monocyclic compounds. In addition, cycloalkanes with olefinic side chains can also be used as cyclic olefins, for example cyclopentyl methacrylate.

Preferably, it is a bridged polycyclic olefin compound. Such polycyclic olefin compounds may have a double bond in the ring (where it is a bridged polycyclic cycloalkene) or may have a double bond in the side chain. In this case, it is a vinyl derivative, allyloxycarboxy derivative or (meth) acryloxy derivative of the polycyclic cycloalkane compound. Such compounds may also have alkyl, aryl or aralkyl substituents.

Examples of polycyclic compounds include bicyclo [2.2.1] hept-2-ene (norbornene), bicyclo [2.2.1] hept-2,5-diene (2,5-norbornadiene), Ethylbicyclo [2.2.1] hept-2-ene (ethylnorbornene), ethyledenbicyclo [2.2.1] hept-2-ene (ethyleneden-2-norbornene), phenylbicyclo [2.2 .1] hept-2-ene, bicyclo [4.3.0] nona-3,8-diene, tricyclo [4.3.0.1 ^2,5 ] -3-decene, tricyclo [4.3.0.1 ^2,5 ]- 3,8-decene- (3,8-dihydrobicyclopentadiene), tricyclo [4.4.0.1 ^2,5 ] -3-undecene, tetracyclo [4.4.0.1 ^2,5 , 1 ^7,10 ] -3-dodecane, ethyledentetracyclo [4.4.0.1 ^2,5 .1 ^7,10 ] -3-dodecane, methyloxycarbonyltetracyclo [4.4.0.1 ^2,5 , 1 ^7,10 ] -3 -dodecane, ethyl credential-9-ethyl-tetracyclo [4.4.0.1 ^2,5, 1 ^7,10] -3- dodecane, penta-cyclo ^{[4.7.0.1 2,5, O, O 3,13} , 1 9 ^{, 12} ] -3- ^pentadecene , pentacyclo [6.1.1 ^3,6 .0 ^2,7 .0 ^9,13 ] -4- ^{pentadecene, hexacycle} To ^{[6.6.1.1 3,6 .1 10,13 .0 2,7 .0} 9,14] -4- hepta-decene, hexadecyl dimethyl bicyclo [6.6.1.1 ^3,6 .1 ^10,13 .0 ^2,7 .0 ^9,14 ] -4-heptadecene, bis (allyloxycarboxy) tricyclo [4.3.0.1 ^2,5 ] decane, bis (methacryloxy) tricyclo [4.3.0.1 ^2,5 ] decane, bis ( Acryloxy) tricyclo [4.3.0.1 ^2,5 ] decane, but is not limited thereto.

Cycloolefinic polymers are prepared using at least one of the cycloolefinic compounds mentioned above, in particular polycyclic hydrocarbon compounds. The method for preparing the cycloolefinic polymer may also use other olefins copolymerizable with the cycloolefinic monomers mentioned above. Examples thereof include ethylene, propylene, isoprene, butadiene, methylpentene, styrene and vinyltoluene.

Most of the olefins mentioned above, in particular cycloolefins and polycycloolefins, can be commercially available. Many cyclic and polycyclic olefins can additionally be obtained by Diels-Alder addition reaction.

Cycloolefinic polymers are described in, for example, Japanese Patent Specifications 1118/1972, 43412/1983, 1442/1986, and 19761/1987, Japanese Patent Laid-Open No. 75700/1975, and 129434/1980. 127728/1983, 168708/1985, 271308/1986, 221118/1988 and 180976/1990, Published European Patent Publication Nos. 0'6'610'851, 0'6 485 893, 0'6'407'870 and 0 6 688 801, which are incorporated herein by reference.

Cycloolefinic polymers can be polymerized in a solvent using, for example, aluminum compounds, vanadium compounds, tungsten compounds or boron compounds as catalysts.

Depending on the conditions, in particular depending on the catalyst used, the polymerization is considered to carry out the ring closure or ring opening of the double bond.

It is also possible to obtain cycloolefin polymerization by free radical polymerization using light or initiator as free radical generator. This applies in particular to acryloyl derivatives of cycloolefins and / or cycloalkanes. This type of polymerization can be carried out in solution or in bulk.

Another preferred plastic substrate includes poly (meth) acrylates. Such polymers are generally obtained by free radical polymers of mixtures comprising (meth) acrylates. The term (meth) acrylate includes methacrylates, acrylates and also mixtures thereof.

Such monomers are well known. Among these, in particular (meth) acrylates derived from saturated alcohols such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, 3 Tertiary butyl (meth) acrylate, propyl (meth) acrylate and 2-ethylhexyl (meth) acrylate; (Meth) acrylates derived from alcohols such as oleyl (meth) acrylate, 2-propynyl (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate; Aryl (meth) acrylates, such as benzyl (meth) acrylate or phenyl (meth) acrylate, wherein the aryl radicals may each be unsubstituted or substituted with up to 4 substituents; Hydroxyalkyl (meth) acrylates such as 3-vinylcyclohexyl (meth) acrylate, bornyl (meth) acrylate;

Hydroxyalkyl (meth) acrylates such as 3-hydroxypropyl (meth) acrylate, 3,4-dihydroxybutyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2 -Hydroxypropyl (meth) acrylate;

Glycol di (meth) acrylates such as 1,4-butanediol di (meth) acrylate, (meth) acrylates of ether alcohols such as tetrahydrofurfuryl (meth) acrylate, vinyloxy Oxyethyl (meth) acrylate;

Amides and nitriles of (meth) acrylic acid, for example N- (3-dimethylaminopropyl) (meth) acrylamide, N- (diethylphosphono) (meth) acrylamide, 1-methacryloyl amido -2-methyl-2-propanol;

Sulfur-containing methacrylates such as ethylsulfinylethyl (meth) acrylate, 4-thiocyanatobutyl (meth) acrylate, ethylsulfonylethyl (meth) acrylate, thiocyanatomethyl (meth ) Acrylate, methylsulfinylmethyl (meth) acrylate,

Bis ((meth) acryloyloxyethyl) sulfide;

Polyfunctional (meth) acrylates such as trimethylloylpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and pentaerythritol tri (meth) acrylate.

In one preferred embodiment of the invention, such mixtures comprise at least 40% by weight of methyl methacrylate, preferably at least 60% by weight, particularly preferably at least 80% by weight, based on the weight of the monomers. .

In addition to the (meth) acrylates listed above, the composition to be polymerized may also comprise methyl methacrylate and other unsaturated monomers copolymerizable with the above-mentioned (meth) acrylates.

Examples thereof include 1-alkene such as 1-hexene, 1-heptene; Branched alkenes such as vinylcyclohexane, 3,3-dimethyl-1-propene, 3-methyl-1-diisobutylene, 4-methyl-1-pentene;

Acrylonitrile; Vinyl esters such as vinyl acetate;

Styrene, substituted styrene with one alkyl substituent on the side chain, for example α-methylstyrene and α-ethylstyrene, substituted styrene with one alkyl substituent on the ring, for example vinyltoluene and p-methyl Styrenes, halogenated styrenes such as monochlorostyrene, dichlorostyrene, tribromostyrene and tetrabromostyrene;

Heterocyclic vinyl compounds such as 2-vinylpyridine, 3-vinylpyridine, 2-methyl-5-vinylpyridine, 3-ethyl-4-vinylpyridine, 2,3-dimethyl-5-vinylpyridine, vinyl Pyrimidine, vinylpiperidine, 9-vinylcarbazole, 3-vinylcarbazole, 4-vinylcarbazole, 1-vinylimidazole, 2-methyl-1-vinylimidazole, N-vinylpyrrolidone , 2-vinylpyrrolidone, N-vinylpyrrolidine, 3-vinyl-pyrrolidine, N-vinylcaprolactam, N-vinylbutyrolactam, vinyloxolane, vinylfuran, vinylthiophene, vinylthiolane , Vinylthiazole, hydrogenated vinylthiazole, vinyloxazole and hydrogenated vinyloxazole;

Vinyl and isoprenyl ethers;

Maleic acid derivatives such as maleic anhydride, methylmaleic anhydride, maleimide, methylmaleimide; And

Dienes such as divinylbenzene.

The amount generally used in such comonomers is 0 to 60% by weight, preferably 0 to 40% by weight, particularly preferably 0 to 20% by weight, based on the weight of the monomers, and the compounds are used individually. Or as a mixture.

The polymerization is generally initiated by known free radical initiators. Examples of preferred initiators include azo initiators well known to those skilled in the art, such as AIBN and 1,1-azobiscyclohexanecarbonitrile, peroxy compounds such as methyl ethyl ketone peroxide, acetylacetone Peroxide, dilauryl peroxide, tertiary butyl per-2-ethylhexanoate, ketone peroxide, methyl isobutyl ketone peroxide, cyclohexanoate peroxide, dibenzoyl peroxide, tertiary butyl peroxybenzoate Tertiary butylperoxy isopropyl carbonate, 2,5-bis (2-ethylhexanoylperoxy) -2,5-dimethyl-hexane, tertiary butylperoxy 2-ethylhexanoate, tertiary butylperoxy 3,5,5-trimethylhexanoate, dicumyl peroxide, 1,1-bis (tert-butylperoxy) cyclohexane, 1,1-bis (tert-butylperoxy) -3,3,5- Trimethylcyclohexane, cumyl hydroperoxide, tertiary butyl hydroperox Id, bis (4-tert-butylcyclohexyl) peroxydicarbonate, mixtures of two or more of the above-mentioned compounds with each other, and mixtures of the above-mentioned compounds with compounds not mentioned, which likewise can form free radicals. have.

Frequently used amounts of these compounds are from 0.01 to 3% by weight, preferably from 0.05 to 1% by weight, based on the weight of the monomers.

The polymers mentioned above can be used individually or as mixtures. For example, various polycarbonates, poly (meth) acrylates or cycloolefinic polymers that differ in molecular weight or monomer composition can be used herein.

The plastic substrates of the invention can be produced, for example, from the molding compositions of the aforementioned polymers. To this end, they are generally produced in thermoplastic molding processes such as extrusion molding or injection molding.

The weight average molar mass (M _W ) of the homopolymers and / or copolymers used according to the invention as molding compositions for the manufacture of plastic substrates can vary widely, and the molar mass is usually used to prepare molding compositions and methods and applications. Matches However, although not intended to be limiting, this is generally 22,000 to 1,000,000 g / mol, preferably 50,000 to 500,000 g / mol, particularly preferably 80,000 to 300,000 g / mol. An example of how to determine these parameters is gel permeation chromatography.

Plastic substrates can also be produced by cell casting processes. Here, for example, a suitable (meth) acrylic mixture is filled into the mold and polymerized. Such (meth) acrylic mixtures generally comprise the (meth) acrylates listed above, in particular methyl methacrylate. The (meth) acrylic mixtures also include the copolymers listed above and may comprise polymers, in particular poly (meth) acrylates, in particular for viscosity control.

The weight average molar mass (M _W ) of the polymer produced by the cell casting process is greater than the molar mass of the polymer used in the molding composition. This provides a number of known advantages. Without wishing to limit this, the weight average molar mass of the polymer produced by the cell casting process is generally from 500,000 to 10,000,000 g / mol.

Preferred plastic substrates produced by the cell casting process are C. The trade name ^R Plexiglas GS manufactured by Rohm GmbH & Co.KG is available.

Molding compositions used to make plastic substrates and acrylic resins may also include additives of any conventional type. Examples thereof include antistatic agents, antioxidants, mold release agents, flame retardants, lubricants, dyes, flow improvers, fillers, light stabilizers, organophosphorus compounds, for example phosphites, phosphorinanes, phospholanes or phosphonates, pigments, Weathering stabilizers and plasticizers. However, the amount of additive is limited with respect to the present application.

Particularly preferred molding compositions comprising poly (meth) acrylates can be purchased under the trade name PLEXIGLAS ^R manufactured by Degussa AG. Preferred molding compositions comprising cycloolefinic polymers are available under the trade names ^R Topas manufactured by Ticona and the trade name ^R Zeonex manufactured by Nippon Zeon. Polycarbonate molding compositions second agent can be, for example, purchase the Bayer (Bayer) is a manufacturing an ^R mark rolron (Makrolon) or General Electric (GEneral Electric) producing ^R Lexan (Lexan).

Particularly preferred plastic substrates comprise at least 80% by weight, in particular at least 90% by weight, of poly (meth) acrylates, polycarbonates and / or cycloolefinic polymers, based on the total weight of the substrate. The plastic substrate is particularly preferably composed of polymethyl methacrylate, which polymethyl methacrylate may comprise conventional additives.

In one preferred embodiment, the impact strength of the plastic to ISO 179/1 substrate is 10kJ / m ^2, preferably from 15kJ / m ^2.

The shape and size of the plastic substrate is not an element of the present invention. Generally commonly used substrates have the form of sheets or panels, the thickness of which is 1 to 200 mm, in particular 5 to 30 mm.

Before providing the plastic substrate to the coating, it can be activated in a suitable way to improve adhesion. For this purpose, for example, the plastic substrate can be treated by chemical and / or physical processes, which particular process depends on the plastic substrate.

The plastic substrate of the present invention is initially provided with an adhesion promoting intermediate layer (b) located between an inorganic coating comprising two polymers (A) and a polymer (B) and a plastic substrate, where water is a polymer ( A) a contact angle of 73 ° or less is formed in the layer, and a contact angle of 75 ° or more is formed in the polymer (B) layer. The contact angle is measured at 20 ° C using a G40 contact angle measuring system manufactured by Kruss, Hamburg, Germany.

The layer thickness for measuring the contact angle is not critical, but water is only in contact with the layer consisting of polymer (A) or polymer (B) respectively. Layer thicknesses of 50 μm or less are generally sufficient. However, the layer should be smooth to allow calibration measurements of the contact angle. This value applies to substantially smooth surfaces. Preparations of this type are known to those skilled in the art. Smooth surfaces provided with sufficient layer thickness naturally form when a flow coating process is used.

The main property of the adhesion promoting layer is that its adhesion to both the plastic surface and the layer which inhibits the formation of water is greater than the adhesion of the layer to the plastic surface. There are many organic polymeric materials that adhere well to waterproof plastic surfaces, but proper adhesion to layers that inhibit water formation requires special properties.

This property is based on the polymer (A) which is located in the adhesion promoting layer and has a polar group, which has low solubility and low swelling property in water. The polarity of the polymer (A) is evident by the low contact angle formed by water with respect to the layer formed from the polymer (A). Such a layer may comprise a small amount of additives or solvent residues, which is essential here that such additives do not affect the contact angle. Thus, the layer of polymer (A) forms a contact angle of 73 ° or less at 20 ° C., and the contact angle of polymer (A) is preferably 50 to 72 °, particularly preferably 65 to 71 °.

The properties of the polymer (A) are not subject to any particular limitation as long as polarity is present, which is reflected in the contact angle formed by water on the surface composed of the polymer (A). Such polarity can generally be achieved through polar groups, which can be components of the main and / or side chains.

Thus, the polymer (A) can be obtained by multiple addition or polycondensation reaction. Examples thereof include polyether, polyester, polycarbonate, polyurethane, epoxy resin and polyamide.

Polyvinyl compounds are another group of compounds suitable as polymers. Examples thereof include polyolefins such as polypropylene, polyethylene; Polyaryl compounds such as polystyrene; Poly (meth) acrylates and polyvinyl acetates. Suitable vinyl compounds for preparing such compounds are listed above.

In order for the polymer (A) to have the contact angles listed above, such polymers may comprise polar groups. Such groups can be incorporated into the polymer (A), for example by selecting a suitable copolymer. Such groups can also be grafted into polymers by graft copolymerization.

Particular polar groups that may be listed are hydroxy, carboxy, sulfonyl, carboxyamide, nitrile and silanol groups. It is preferably a component of a macromolecular compound comprising a nonpolar group such as an alkyl, alkylene, aryl or arylene group.

The polar ratio of the nonpolar groups in the polymer (A) is chosen to adhere to both the waterproof, i.e., the layer which inhibits the formation of hydrophilic water droplets. The polarity should not be so high that the material of the adhesion promoting layer itself is water soluble or water swellable. The degree of swelling at saturation with water at 20 ° is 10% by volume or less, preferably 2% by volume or less. However, the polarity of the polymer (A) is also not so low that this compound is dissolved in a completely nonpolar solvent such as naphtha. Most suitable materials are dissolved in suitable polar organic solvents such as chlorinated hydrocarbons, esters, ketones, alcohols, ethers or mixtures thereof with aromatic compounds.

The necessary coordination of affinity with two adjacent layers is generally achieved when the material of the adhesion promoting layer comprises between 0.4 and 100 milliequivalents of polar group per 100 g of polymeric material.

The polar action of the polar groups is different. This in turn increases nitrile, hydroxy, primary carboxamide, carboxy, sulfonyl or silanol. The strong polar action lowers the content required of the polymeric material. For low polar groups, 4 to 100 milliequivalents of polar group per 100 grams of polymer material are used, whereas 0.4 to 20 milliquivalents per 100 grams of polymer material is sufficient. If the selected content of the polar group is too low, the layer which inhibits the formation of water does not have sufficient adhesion. On the other hand, if the content of the polar group is too high, the water swellability is excessively increased, and thus the adhesion is reduced.

The polarity of the polymers comprising hydroxy groups and obtained by polycondensation or multiple additions, in particular, reacts with silanes having at least two hydrolyzable groups per silicon atom, for example halogen atoms, alkoxy groups and / or aryloxy groups. Can be increased by.

Examples of such compounds include tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane; Trialkoxysilane, for example, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, n-propyl-trimethoxysilane, n-propyltriethoxysilane, isopropyl-triethoxysilane ; Dialkoxysilanes such as dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxy-silane, diethyldiethoxysilane, di-n-propyldimethoxy-silane, di-n-propyldiethoxysilane, Diisopropyl dimethoxysilane and diisopropyl diethoxysilane are mentioned.

Polymers obtainable by free radical polymers of vinyl compounds may also be modified, such as polymers obtainable by polymerisation or multiple additions.

In order to modify such polyvinyl compounds, in particular they can be prepared with silanes comprising vinyl groups which are not hydrolyzed. Examples of particularly suitable vinyl silane compounds include the following:

CH ₂ = CH-Si (OCH ₃ ) ₃ , CH ₂ = CH-Si (OC ₂ H ₅ ) ₃ , CH ₂ = CH-SiCl ₃ ,

CH ₂ = CH-Si (CH ₃ ) (OCH ₃ ) ₂ , CH ₂ = CH-CO ₂ -C ₃ H ₇ -Si (OCH ₃ ) ₃ ,

CH ₂ = CH-CO ₂ -C ₃ H ₇ -Si (OCH ₃ ) ₃ , CH ₂ = C (CH ₃ ) -CO ₂ -C ₃ H ₇ -Si (OCH ₃ ) ₃ ,

CH ₂ = C (CH ₃ ) -CO ₂ -C ₃ H ₇ -Si (OC ₂ H ₅ ) ₃ and CH ₂ = C (CH ₃ ) -CO ₂ -C ₃ H ₇ -SiCl ₃ .

Preference is also given to polymers (A) having groups which are crosslinked during and / or after the formation of the intermediate layer (B). Silanes having three hydrolyzable groups and one vinyl group are particularly suitable for this purpose and examples of such silanes are listed above.

The polar polymer (A) may be present individually in the adhesion promoting polymer layer (b) or as a mixture.

The amount of polymer (A) in the adhesion promoting polymer layer (b) can vary widely. This depends in particular on the nature and polarity of the polymer (B). The proportion is generally 30 to 95% by weight, preferably 40 to 90% by weight, particularly preferably 50 to 85% by weight, based on the weight of the intermediate layer (b), but is not intended to be limiting.

In addition to the polar polymer (A), the adhesion promoting intermediate layer (b) comprises at least one polymer (B) having nonpolar properties. This property is reflected at the contact angle formed by water with respect to the surface consisting of polymer (B). Such layers may comprise small amounts of additives or some solvent residues, but it is essential that these additives do not affect the contact angle. The solubility of polymer (B) in water is very low. It is generally less than 1 g / l.

The properties of the polymer (B) are not particularly limited by the contact angle formed by water with respect to the surface composed of the polymer (B) as long as there is a high level of hydrophobic property. Thus, polymeric compounds suitable as polymer (B) have a high proportion of nonpolar groups.

The hydrophobic nature of the polymer (B) is evident by the large contact angle formed by the water in the layer of the polymer (B). Therefore, the contact angle observed for the polymer (B) layer is at least 75 °, and the contact angle of the polymer (B) is preferably 75 to 90 °, particularly preferably 76 to 80 °.

Thus, the polymer (B) can be obtained by multiple addition or polycondensation reaction. Examples are polyethers, polyesters, polycarbonates, polyurethanes and polyamides.

Another group of compounds suitable as polymers (B) are polyvinyl compound groups. Examples thereof include polyolefins such as polypropylene, polyethylene; Polyaryl compounds such as polystyrene; Poly (meth) acrylates and polyvinyl acetates. Suitable vinyl compounds for preparing such polymers are listed above.

To some extent, the polymers mentioned above comprise polar groups. This is not important unless the polarity result is that the contact angle formed by water with the layer composed of polymer (B) is outside the range defined above. It should be mentioned that the polarity of such polymers can be reduced by hydrophobic side chains such as alkyl chains in such a way that the above mentioned contact angle values are achieved.

Preferred polymers (B) can be obtained by free radical polymerizing a mixture comprising the following components, based on the weight of the vinyl compound:

50 to 100% by weight of (meth) acrylate,

0 to 60% by weight of methyl (meth) acrylate,

                    Preferably 0 to 50% by weight,

0-60 wt% ethyl (meth) acrylate,

                  Preferably 0 to 50% by weight,

0 to 100% by weight of C ₃ -C ₆ (meth) acrylate,

≥ 0 to 50% by weight of C ₇ (meth) acrylate,

0-5% by weight of polyfunctional (meth) acrylate,

Comonomer 0-50% by weight,

0 to 30% by weight of vinylaromatic compound and

0 to 30 weight percent vinyl ester.

The nonpolar polymer (B) may be present individually in the adhesion promoting intermediate layer (b) or as a mixture.

The amount of polymer (B) present in the adhesion promoting intermediate layer (b) can vary widely. This depends in particular on the nature and polarity of the polymer (B). The proportion thereof is generally 5 to 70% by weight, preferably 10 to 60% by weight, particularly preferably 15 to 50% by weight, based on the weight of the adhesion promoting intermediate layer (b), but is intended to be limited thereto. It is not.

The intermediate layer (b) may also comprise a conventional adhesive. Specific examples thereof are surfactants and flow regulators.

An example of a method for preparing the intermediate layer (b) is to use a mixture of polymer (A) and polymer (B) in a suitable solvent or dispersion medium to produce a coating mixture which may comprise the adhesives listed above. Using a solvent mixture may be necessary because the polarities of the polymers (A) and (B) are different.

The coating mixtures listed above can be applied to the plastic substrate in any known manner. Examples thereof are dipping, spraying, doctoring, flow coating and coating by rollers or rolls.

The coating so applied is generally cured or within a relatively short time, for example for 1 minute to 1 hour, generally for about 3 to 30 minutes, preferably for about 5 to 20 minutes, at relatively low temperatures, for example, It may be dried at 70 to 110 ℃, preferably about 80 ℃.

The thickness of the intermediate layer is not particularly important. However, it is chosen relatively low if possible in terms of cost, and the lower limit is provided by the stability of the entire coating a and coating b. However, this is not intended to be limiting, and after curing, the thickness of the adhesion promoting intermediate layer is 0.05 to 10 mu m, preferably 0.1 to 2 mu m, particularly preferably 0.2 kPa to mu m. The layer thickness of the coating a and / or the coating b can be measured by transmission electron microscopy (TEM).

In one particular embodiment of the invention, the contact angle formed by water with respect to the intermediate layer (b) at 20 ° C. is 63 ° to 80 °, in particular 65 ° to 78 °, particularly preferably 68 ° to 77 °, It is not intended to limit this.

After drying the adhesion promoting intermediate layer (b), an inorganic film (a) which suppresses the formation of water droplets is coated.

The term "inhibiting droplet formation" means that the water droplet forms a contact angle of 20 ° or less, preferably 10 ° or less, on the surface. These parameters are measured at 20 ° C. using a G40 contact angle measuring system manufactured by Crus, Hamburg, Germany.

For the purposes of the present invention, the term "inorganic" means that the carbon content of the inorganic coating, based on the weight of the inorganic coating (a), is 25% by weight or less, preferably 17% by weight or less, very particularly preferably 10 It means less than or equal to weight percent.

Particular inorganic coatings that may be applied may be polysiloxanes, silane cocondensates and silica sol, the carbon content of which is limited as listed above.

Silane cocondensates that can be used for the preparation of the coating (a) are known per se and are used as additives in polymeric glaze materials. Its inorganic properties provide excellent resistance to UV radiation and weathering effects.

Such silane cocondensates can be obtained in particular via polycondensation or hydrolysis of organosilicon compounds of formula (I):

R ¹ _n SiX _4-n

In Formula I above,

R ¹ is a group having 1 to 20 carbon atoms,

X is an alkoxy radical or halogen having 1 to 20 carbon atoms,

n is an integer from 0 to 3, preferably 0 or 1,

The various radicals X or R ¹ may in each case be the same or different.

The term "group of 1 to 20 carbon atoms" is characterized by radicals of organic compounds having 1 to 20 carbon atoms. It includes alkyl groups having 1 to 20 carbon atoms, cycloalkyl groups, aromatic groups, alkenyl groups and alkynyl groups, and in particular hetero having oxygen atoms, nitrogen atoms, sulfur atoms and phosphorus atoms, in addition to carbon and hydrogen atoms Aliphatic and heteroaromatic groups. The groups mentioned can be branched or straight chained, wherein the radical R ¹ can be substituted or unsubstituted. Among the substituents, in particular halogen, groups having 1 to 20 carbon atoms, nitro groups, sulfonic acid groups, alkoxy groups, cycloalkoxy groups, alkanoyl groups, alkoxycarbonyl groups, sulfonic acid ester groups, sulfinic acid groups, sulfinic acid ester groups, Thiol groups, cyanide groups, epoxy groups, (meth) acryloyl groups, amino groups and hydroxy groups. For the purposes of the present invention, the term "halogen" means fluorine atom, chlorine atom, bromine atom or iodine atom.

Among the preferred alkyl groups are methyl, ethyl, propyl, isopropyl, 1-butyl, 2-butyl, 2-methylpropyl, tertiary butyl, propyl groups and 2-methylbutyl groups.

Examples of preferred cycloalkyl groups are cyclopropyl, cyclobutyl, cyclopropyl, cyclohexyl and cycloheptyl groups and cyclooctyl groups, which are optionally substituted by branched or straight chain alkyl groups.

Examples of preferred alkoxy groups include methoxy, ethoxy, propoxy, butoxy, tert-butoxy, hexyloxy, 2-methylhexyloxy, decyloxy group or dodecyloxy group.

Examples of preferred cycloalkoxy groups are cycloalkoxy groups, the hydrocarbon radicals of which are any of the preferred cycloalkyl groups mentioned above.

The radical R ¹ is very particularly preferably a methyl or ethyl group.

For alkoxy groups and halogens having 1 to 20 carbon atoms, with regard to the definition of group X in formula (I), reference is made to the definitions mentioned above. Group X is preferably a methoxy or ethoxy radical, bromine or chlorine atom.

These compounds can be used individually or as mixtures for preparing silane cocondensates.

Based on the weight of the condensed silane, the silane compound used to have four alkoxy groups or halogen atoms is preferably at least 80% by weight, in particular at least 90% by weight.

Tetraalkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetraiso-propoxy-silane and tetra-n-butoxysilane.

Tetramethoxysilane and tetraethoxysilane are particularly preferred. In one particular embodiment of the invention, the proportion of such particularly preferred tetraalkoxysilanes is at least 80% by weight, in particular at least 90% by weight, based on the weight of the silane compound used.

In another aspect of the present invention, a silane condensate may also be used which comprises colloidally dispersed SiO ₂ particles. Such a solution can be obtained by a sol-gel process, in particular a condensation process of tetraalkoxysilane and / or tetrahalosilane.

Aqueous coating compositions are usually mentioned above by hydrolyzing the organophosphorus compound in an amount sufficient for the hydrolysis process, ie in an amount of 0.5 mol of water per mole of the group intended for hydrolysis, for example an alkoxy group, preferably an acid catalyst. It can be prepared from one silane compound. Examples of acids which may be added are inorganic acids, such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, or the like, or organic acids, such as carboxylic acid, organic sulfonic acid, or the like, or acidic ion exchange groups, and generally during hydrolysis reactions. PH is 2 to 4.5, preferably 3.

When the reactants are combined, a rise in temperature is generally observed. In certain cases, it may be necessary to introduce external heat to initiate the reaction by heating the mixture to 40-50 ° C. In general, the reaction is carried out to suppress the reaction temperature from exceeding 55 ° C. The reaction time is generally relatively short, usually less than 1 hour, for example 45 minutes.

The silane compound may be condensed to obtain a polymer having a weight average molar mass (M _W ) of generally 100 to 20 000 g / mol, preferably 200 to 10 000 g / mol, particularly preferably 500 to 1500 g / mol. An example of a method of measuring this molar mass is NMR spectroscopy.

Examples of methods for terminating the condensation reaction include cooling to a temperature below 0 ° C. or increasing the pH using a suitable base such as an organic base such as an amine, alkali metal hydroxide or alkaline earth metal hydroxide. It is to let.

For further operation, some water / alcohol mixtures and volatile acids can be removed from the reaction mixture, for example by distillation.

Silane co-condensates which can be used according to the invention are, for example, in the form of zinc compounds and / or other metal compounds, for example cobalt compounds, copper compounds or calcium compounds and especially octoates or nathalenates thereof. And a curing catalyst. Although not intended to be limiting, the content of the curing catalyst is generally from 0.1 to 2.5% by weight, in particular from 0.2 to 2% by weight, based on the total silane cocondensate. For example, zinc naphthalenate, zinc octoate, zinc acetate, zinc sulfate and the like can be enumerated.

Also, as coatings that suppress water droplet formation, oxide layers, in particular semimetals and metal oxides, can be enumerated. Suitable compounds are in particular oxides and hydroxides derived from silicon, aluminum, titanium, zirconium, zinc and / or chromium.

These oxides can be used individually or as a mixture, for example in the form of mixed oxides. Such oxides and / or hydroxides should have the lowest solubility in water and the solubility in water at 20 ° C., for example, should be 1000 μg / l or less, preferably 200 μg / l or less.

Such oxides can be applied, for example, in the form of colloidal solutions obtained by hydrolyzing an alkoxy compound. Such colloidal solutions are described, for example, in EP 0 149 182, 0 826 663 and 0 850850 203, and EP 1 022 318.

The particle size of these oxide particles is not critical, but the transparency depends on the particle size. The size of the particles is preferably at most 300 nm, in particular 1 to 200 nm, preferably 1 to 50 nm.

The coating compositions mentioned above include the trade names ^R Ludox (manufactured by Grace, Worms); Trade name ^R Levasil (manufactured by Bayer, Leverkusen); The trade name ^R Klebosol (manufactured by Clariant) is commercially available.

The coating composition for producing the inorganic coating (a) may also include conventional additives and processing aids. Examples thereof are in particular surfactants and flow regulators.

The above-mentioned coating composition for preparing the inorganic coating (a) may be applied to the plastic substrate using any known method, examples of which are listed above.

The surface finish applied in this way is fully cured and generally within a relatively short time, for example within 0.5 minutes to 1 hour, usually about 1 to 30 minutes, preferably 3 to 20 minutes, at relatively low temperatures, eg For example, a film having excellent adhesion can be obtained at 60 to 110 ° C, preferably about 80 ° C.

The layer thickness of the inorganic coating (a) is relatively insignificant. However, although not intending to be limiting, the value of this variable after the curing process is generally from 0.05 to 2 μm, preferably from 0.05 Pa to 1 μm, particularly preferably from 0.05 to 0.5 μm. The layer thickness range of the film a and the film b is preferably 0.1 to 3 mu m.

The plastic article of the present invention can be excellently deformed without adversely affecting the film which suppresses the formation of water droplets. Such forming processes are known to those skilled in the art. In this process, the plastic particles are heated and formed in a suitable template manner. The temperature at which the forming process is performed depends on the softening point of the substrate from which the plastic product is made. This process is especially used for the processing of cast transparent sheets.

The plastic product of the present invention, which is provided with a film for inhibiting the formation of water droplets, has a high scrub resistance. Scrub resistance according to DIN 53778 is preferably at least 3000 cycles, in particular at least 5000 cycles, particularly preferably at least 10000 cycles.

In one particular embodiment of the invention, the plastic article is transparent and has a transparency (τ _{D65 / 10} ) according to DIN 5033 of at least 70%, preferably at least 75%.

While not intending to limit this, plastic products preferably have an elastic modulus in accordance with ISO 527-2 of at least 1000 MPa, in particular at least 1500 MPa.

Plastic products of the invention generally have high weather resistance. For example, the weather resistance according to DIN 53387 (Xenotest) is more than 5000 hours.

While not intending to limit this, the yellowing index according to DIN 6167 (D65 / 10) of preferred plastic products remains below 8, preferably below 5 even after extended UV conditions for more than 5000 hours.

The plastic products of the invention can be used in the construction sector, for example, in particular for producing green houses or greenhouses, or can be used as noise barriers.

The present invention will be described in more detail by the following examples of the present invention, but should not be construed as limiting the examples.

Inventive Example 1

Preparation of Adhesion Promoting Intermediate Layers

A first polymer consisting of 88% methyl methacrylate and 12% of gamma -methacryloyloxypropyltrimethoxysilane and a second polymer consisting of 20% methyl methacrylate and 80% butyl methacrylate were prepared in butyl acetate. It is melt | dissolved in the ratio of 1: 1, and is apply | coated by fluid-coating a thin layer to PMMA sheet. The run is terminated and the coated sheet is dried in an oven at 80 ° C. for 20 minutes.

The contact angle of the dried intermediate layer with water is 76.5 ° at 20 ° C. In contrast, the contact angle of the intermediate layer produced in the original polymer is about 66 ° at 20 ° C. and hydrolyzes the methoxy group of γ-methacryloyloxypropyltrimethoxysilane to some extent. The contact angle of the intermediate layer consisting of the second copolymer is 77.5 ° at 20 ° C.

Preparation of Layers That Inhibit Drop Formation

Anionic silica sol 25% (solid content 30%), 0.1% potassium salt of 3-sulfopropyl ester of o-ethyldithiocarboxylic acid and 0.4% ethoxylated fatty alcohol are made up to 100 parts with deionized water, and the adhesion promoting layer is The sheet provided is coated by flow coating in a thin layer.

In order to suppress and prevent foam formation in the coating liquid, a commercially available antifoaming agent is added if necessary.

The layer thicknesses of the active ingredient layer and the adhesion promoting layer can be set as desired by dilution with deionized water and, if desired, additional surfactants, if desired. In particular, for sheets of relatively long length, it is advantageous to ensure that the layer thickness at the bottom end is not too high and to increase the dilution to minimize the layer thickness slope from the top and bottom. The layer thickness of very thin layers can be measured by thin sections with transmission electron microscopy.

After air drying, the sheet provided with the layer which inhibits the formation of water droplets and the adhesion promoting layer is dried in a convection oven at 80 ° C. for 20 minutes.

Adhesion of the coating is measured by DIN # 53778 using M 105 / A wet scrub tester manufactured by Gardner. Measure the value at 12,000 cycles.

Plastic products are also thermoformed. Thermoforming is achieved by heating the coating sheet to 150-170 ° C. in a convection oven. The choice of temperature depends on the heat resistance of the substrate. Unlike cast PMMA, extruded PMMA having a plastic comonomer, for example acrylate, and having a low molecular weight, even relatively low temperature, is sufficient. In the case of cast PMMA having a molecular weight of at least about 1 million to 2 million and consisting mainly of pure MMA homopolymers, high temperatures are sometimes used with weakened crosslinks. Once the sheet is softened, it is curved and cooled in three semicircle molds with the described bending radius.

After forming using a bending radius of 47.5 mm, the sheet produced as in Example 1 did not show cloudy or cracked in the coating, and was excellent in suppressing the formation of low water droplets at the contact angle.

Evaluation of the suppression of water droplet formation by the contoured substrate can only be made with the naked eye, since the test specimen drawn by the contour cannot be measured. Inhibition of water formation is evaluated here as qualitatively superior.

Subsequently, the wet scrub test cannot be performed on the contoured test piece because such a test also requires the substrate to be flat.

Comparative Example 1

Example 1 is substantially repeated except that a second copolymer of 20% methyl methacrylate and 80% butyl methacrylate is present in the adhesion promoting polymer layer. The contact angle of the intermediate layer is 66 °.

Similarly, scrub resistance is 12,000 cycles. In thermoforming, severe clouding appears, followed by poor suppression of water formation, as assessed visually.

Example 2 of the Invention

Example 1 was repeated with a first copolymer consisting of 88% methyl methacrylate and 12% of γ-methacryloylpropyltrimethoxysilane and a agent consisting of 20% methyl methacrylate and 80% butyl methacrylate. The two copolymers are dissolved in butyl acetate at a ratio of 8: 1 and applied thinly with PMMA sheets by flow coating. The contact angle for the interlayer is 69.5 °.

Scrub resistance is 20,00 cycles. After thermoforming, the sheet is transparent and effectively suppresses water droplet formation.

Comparative Example 2

Example 1 is substantially repeated, wherein the adhesion promoting intermediate layer comprises a second polymer consisting of 19% methyl methacrylate, 1% methacrylic acid and 80% butyl methacrylate. The contact angle of the intermediate layer is 61 °. The intermediate layer composed of the second polymer has a contact angle of 20 ° to about 55 °.

In thermoforming, severe clouding is evident, and the suppression of water formation, as assessed visually, is poor.

Claims (23)

A water droplet suppressing plastic article comprising a plastic substrate, at least one inorganic film (a) that inhibits water droplet formation and an adhesion promoting intermediate layer (b) located between the inorganic film and the plastic substrate, The intermediate layer comprises two polymers (A) and a polymer (B), water forms a contact angle of not more than 73 ° in the polymer (A) layer at 20 ° C., and water is 75 in the polymer (B) layer at 20 ° C. A plastic product, characterized by forming a contact angle of at least °. The plastic article of claim 1, wherein the plastic substrate comprises a cycloolefin copolymer, polyethylene terephthalate, polycarbonate, and / or poly (meth) acrylate. The plastic article of claim 2, wherein the plastic substrate consists of polymethyl methacrylate. The plastic article according to claim 1, wherein the impact strength according to ISO 179/1 of the plastic substrate is at least 10 kJ / m ^{2. 5} . 5. The plastic product according to claim 1, wherein the thickness of the plastic substrate is in the range of 1 to 200 mm. 6. 6. The plastic product according to claim 1, wherein the solubility of the polymer (A) in water is less than 1 g / l. 7. The plastic product according to claim 1, wherein the solubility of the polymer (B) in water is less than 1 g / l. 8. The plastic product according to claim 1, wherein the thickness range of the adhesion promoting intermediate layer (b) is from 0.05 to 2.0 μm. 9. The method according to any one of claims 1 to 8, wherein the ratio of the polymer (A) in the adhesion promoting intermediate layer (b) is 30 to 95% by weight based on the weight of the adhesion promoting intermediate layer (b). Made, plastic products. 10. The method according to any one of the preceding claims, wherein the ratio of polymer (B) in the adhesion promoting intermediate layer (b) is 5 to 70% by weight, based on the weight of the adhesion promotion intermediate layer (b). Made, plastic products. The plastic article according to claim 1, wherein the polymer (A) is a vinyl polymer modified with a polar group. The plastic product according to claim 1, wherein the polymer (B) is an alkyl (meth) acrylate. The plastic product according to claim 1, wherein the polymer (B) is obtained by free radical polymerization of a mixture comprising the following components, based on the weight of the vinyl compound. 50 to 100% by weight of (meth) acrylate, 0 to 60% by weight of methyl (meth) acrylate, 0-60 wt% ethyl (meth) acrylate, 0 to 100% by weight of C ₃ -C ₆ (meth) acrylate, ≥ 0 to 50% by weight of C ₇ (meth) acrylate, 0-5% by weight of polyfunctional (meth) acrylate, Comonomer 0-50% by weight, 0 to 30% by weight of vinylaromatic compound and 0 to 30 weight percent vinyl ester. The plastic product according to any one of claims 1 to 13, wherein the carbon content of the inorganic coating (a) is 17% by weight or less based on the weight of the coating (a). The plastic article according to claim 1, wherein the inorganic coating (a) can be obtained by curing a colloidal solution of an inorganic and / or organometallic compound. The composition according to any one of claims 1 to 15, wherein the inorganic coating (a) contains 80% by weight or more of alkyltrialkoxysilane and / or tetraalkoxysilane based on the content of the condensable silane. Plastic product, characterized in that it can be obtained by condensation. The plastic article according to claim 1, wherein the inorganic coating (a) comprises a condensable polysiloxane having a molar mass range of 500 to 1,500 g / mol. 18. Plastic product according to any one of the preceding claims, characterized in that the thickness range of the coating (a) and the coating (b) is from 0.1 to 3 mu m. The plastic product according to claim 1, characterized in that the scrub resistance according to DIN 53778 is at least 10,000 cycles. The plastic product according to claim 1, characterized in that the elastic modulus according to ISO 527-2 is at least 1,500 MPa. The plastic product according to claim 1, characterized in that the weather resistance according to DIN 53 387 is at least 5,000 hours. 22. Plastic product according to any one of the preceding claims, characterized in that the transparency according to DIN 5033 is at least 70%. A contact angle comprising two polymers (A) and a polymer (B), wherein water forms a contact angle of 73 ° or less in the polymer (A) layer at 20 ° C., and water has a contact angle of 75 ° or more in the polymer (B) layer at 20 ° C. (A) applying and curing the adhesion promoting film (b) to form a plastic substrate and A method for producing a water droplet suppressing plastic article according to any one of claims 1 to 23, comprising the step (b) of applying and curing an inorganic coating (a) which inhibits water droplet formation.